In a conventional light emitting diode (LED) package, especially UV LED, having a cavity, the cavity has to be sealed for insulating the LED die, and the cavity is kept vacuum or noble gas atmosphere in order to prevent the LED die within the cavity from suffering damage issue caused by water vapor. Thus, the method of manufacturing the conventional LED package needs a large vacuum chamber to make a vacuum environment for exhausting the air that surrounds the LED die. However, the cost of the large vacuum chamber is very high, whereas the large vacuum chamber needs to spend a lot of time (pulling vacuum so as to be) changing the operating environment within the large vacuum chamber from the atmospheric pressure to an appropriate vacuum. Therefore, generally, it will spend much time and money manufacturing the LED package.